What Are Brine Shrimp?

Brine shrimp are crustaceans that are classified in the phylum Arthropoda (the largest phylum in the animal kingdom, which includes insects and other creatures with jointed legs and exoskeletons). They live in inland bodies of saltwater, such as the Great Salt Lake, but not in the ocean, where they would have too many predators.

The female brine shrimp lays encapsulated eggs, or cysts, which remain dormant until the right hatching conditions. These eggs can survive for years when dried and then, when added to salt water, hatch literally overnight! The hatched shrimp larvae are called nauplii (singular is ‘nauplius’) and have a different anatomical structure than adult brine shrimp. A nauplius has only one eye, called a nauplier eye and has an extra pair of antennae with hairlike setae for swimming. The nauplii molt, or shed their exoskeleton, about 12 hours after hatching. This brings them into the second larval stage. After several more moltings, they reach the adult stage; it only takes about eight days to mature from the time they hatch. (You can see an early nauplius stage in this picture of a brine shrimp.)

Adult brine shrimp have a pair of compound eyes as well as the nauplier eye. They also have 11 pairs of phyllopods or leg-like appendages. The structure of the phyllopods are designed for different functions: some are for swimming and the others are for scraping and filtering algae (the shrimp’s primary food source).

Mature brine shrimp might grow to as much as half an inch in length and live for up to three months.

Hatching & Raising Brine Shrimp

Use a glass container as a hatching tank for the brine shrimp, either a wide-mouth quart jar or a shallow glass pan at least two inches deep (this will work best). Fill the container with one quart of salt-water solution: mix 1 to1-1/2 teaspoons of sea salt mixture or non-iodized table salt per cup of bottled water. (If you want to use tap water, let it sit for an hour so the chlorine settles. You can also use rock or aquarium salt.) The shrimp will die in salt water that is either too weak or too strong.

Sprinkle about one sixteenth of a teaspoon of brine shrimp eggs into the dish: you don’t need to cover more than one square inch on the surface of the water. Leave the container in a room where bright sunlight can reach it. Your brine shrimp should start hatching in just 24 hours!

The shrimp will live 1-3 days without food. If you want to keep them longer for a more in-depth study, feed them a very tiny amount of yeast – a few ‘grains’ as needed. You might also need to change the water occasionally, if it gets cloudy. Clean out unhatched eggs from the top of the container, which will allow more oxygen to get into the water.

Observing Brine Shrimp

You can study your brine shrimp close up with a magnifying glass, stereo microscope, or compound microscope. Use a pipet or medicine dropper to ‘catch’ some of the shrimp and transfer them with sufficient water into a petri dish for easy observation. Look at them closely with low power (10-30x) magnification. What parts of the brine shrimp can you identify? What are their swimming habits? Eating habits? How do they use their phyllopods? How do they respond to light? If you can, compare the larval stage with the adult stage. Keep track of your observations in a notebook and include sketches of the shrimp.

With a compound microscope, you can see a specimen at much higher magnification (40-400x). This will allow you to see details like the hairlike setae on the phyllopods. Make a wet mount slide by adding 1-3 drops of water with a brine shrimp onto a concave slide, and placing a slide coverslip over it. You can keep track of your observations with our printable microscope worksheet.

Brine Shrimp Experiments: Effect of pH and Environmental Changes

Learn about the effects of the surrounding conditions on brine shrimp! To start, test the pH level in the brine shrimp’s tank water: ideal conditions are a pH of around 8, but no lower than 5 and no higher than 10. Use pH paper for the test. To raise the pH level in the tank, add a little bit of baking soda.

Discover more with a project where you change the tank environment by adding pollutants. Transfer about an equal number of brine shrimp to several petri dishes to be your test samples. Try adding 1-3 drops of a different solution to the water in each petri dish: vegetable oil, soap, vinegar, ammonia, or anything else that comes to mind. Observe the samples at low power magnification and record what’s going on. How do the pollutants affect the sample? Is there a difference visible in twenty minutes? One hour? Three? How might you counteract the pollutants?

You can also try hatching several batches of shrimp at a time, using different hatchery conditions for each batch. Fill 3-4 petri dishes with different solutions: you might use plain tap water, water with a low pH (acidic), and regular salt water to be the control that you can compare the results to. Before you start, hypothesize which solution will have the best results and which will have the worst. Sprinkle a small amount of eggs into each dish. After 24 hours, check on the dishes again. Has anything happened? What are the results after 48 hours? 72 hours? Use a magnifying glass for your observations, and make sketches. Were you right about which solutions would work best and worst? How do you think factors such as temperature (colder or warmer) or more or less light might affect the hatching success rate of the brine shrimp?